Exhaust tube and top cap assembly



Feb. 7, 1961 c. E. BEATON ETAL 2,971,111

EXHAUST TUBE AND TOP CAP ASSEMBLY Filed Nov. 13, 1957 5/ INVENTORS CLARENCE E. BEATON WILLIAM W. HERRICK ATTORNEY United States Patent EXHAUST TUBE AND TGP CAP ASSEMBLY Clarence E. Beaten and William W. Herrick, Emporium, Pa., assignors, by mesne assignments, to Sylvania Eleetric Products Inc., Wilmington, Deh, a corporation of Delaware Filed Nov. 13, 1957, Ser. No. 696,080

3 Claims. (Cl. 313-290) This invention relates to an electron discharge device of the type normally provided with a top metallic terminal sealed into the bulb of the device, which terminal is connected internally of the device to an electrode, as shown for example in the patents to Grimm 2,558,357 and Eitel et a1. 2,577,239. This terminal is adapted to be connected externally of the tube to one pole of an external circuit.

It is an object of this invention to provide a terminal member in the form of an internally constricted metallic sleeve with glass fused within the sleeve to insure an air tight seal between the metal sleeve and the glass.

It is a further object of the invention to provide a structure which is conducive to the manufacture of such devices with minimum shrinkage, as, for example, due to glass being sucked into the device due to bulb evacuation during tipping off.

How these and other objects are cfiectuated will be understood upon consideration of the following specification when taken in conjunction with the accompanying drawing in which:

Fig. 1 is a perspective view of an electron discharge device provided with the terminal of this invention, part of the bulb being broken away.

Fig. 2 is a vertical cross section taken axially through the upper portion of the device prior to the fusing of the glass tubulation into the sleeve and prior to a tipping 01f operation.

Fig. 3 is a sectional view through the sleeve and seal, after sealing the opening in the sleeve and after removing the excess tubulation, as by a tipping oil operation.

Fig. 4 is a modification of the sleeve structure and shows a glass tubulation resting on a thickened inner portion of the sleeve.

Now referring to the drawings in greater detail, at there is shown an electron tube, here exemplified as a type 1133 having an anode 12 with a sleeve 14 integrated with the anode 14 by welding or otherwise. The metal sleeve is cylindrical in shape and one third down from the upper end thereof it has a circular restricted portion forming a seat 16. The restriction may be formed by indenting the wall of the sleeve as by rolling in a groove 18 into the sleeve or by nodulesforced into the hollow of the sleeve. Within the sleeve is positioned a glass tubulation 20 whose external diameter is barely less than the inside diameter of the sleeve. The indentation of the sleeve is such as to bring the innermost portion of the indentation to a distance no greater than the internal diameter of the glass tubulation so as to leave an unrestricted passage for the evacuation of the glass envelope or bulb 15. Prior to bulb evacuation through the tubulation, the lower end of the tubulation 20 is seated against the seat 16 and sealed to the sleeve by suitable application of regulated heat to the glass and metal sleeve adjacent the seat. The seat insures the proper seating of the glass and uniformity as to amount of glass Within the metal sleeve. The internal seat inhibits the sucking in of the glass bulb during evacuation and tipping off of the tubulation, as will be understood.

After bulb evacuation, the tubulation is tipped off by application of fine tip flames immediately above the top of sleeve 14, the glass then fusing into a globule as indicated at 22 in Figs. 1 and 3. The surface tension of the glass prevents it from being sucked from its seat into the lower portions of the sleeve or into the bulb. Since the tipping oil is a machine process with the flames always at a predetermined height with relation to the upper edge of the sleeve, the quantity of glass in the globule within the sleeve is a constant, thus insuring uniformity of product and adequate supply of glass for eiiecting the sealing operation.

In Fig. 4 a modification of the invention is disclosed wherein a metal sleeve 24 corresponding to sleeve 14 in Figs. 1 to 3 is initially formed with two integral internal diametrical bosses 26 to seat the glass tribulation. So, obviously, the internal seat 16 may be made in the form of a solid annular enlargement on the inner Wall of the sleeve.

Having thus described the invention, what is claimed is:

1. An electron device including an evacuated bulb, an electrode in the upper end of the bulb having aiiixed thereto a hollow elongated member, said elongated member extending through the upper Wall of the bulb, a restriction within the hollow elongated member intermediate its ends, and a globule of glass sealed in the upper end of the hollow member substantially flush with the upper end thereof and above the restriction.

2. An electron device including an evacuated bulb, an electrode in the upper end of the bulb having afiixed thereto a hollow metallic elongated member, said elongated member extending through the upper wall of the bulb and forming a terminal member, a restriction within the hollow elongated member intermediate its ends, and a globule of glass sealed in the upper end of the hollow member substantially flush with the upper end of the member and above the restriction.

3. An electron device including an evacuated bulb, an electrode in the upper end of the bulb having aflixed thereto a hollow elongated metallic member, said elongated member extending through the upper wall of the bulb and forming a terminal member, a restriction within the hollow elongated member only intermediate its ends, and a globule of glass in the upper end of the hollow member substantially flush with the upper end] of the member and above the restriction sealing the opening in the metallic member.

References Cited in the file of this patent UNITED STATES PATENTS 1,647,238 Manthorne Nov. 1, 1927 1,858,676 McCullough May 17, 1932 1,897,761 McCullough Feb. 14, 1933 1,941,107 Parker Dec. 26, 1933 1,965,589 Foulke July 10, 1934 2,093,567 McCullough Sept. 21, 1937 2,112,034 Livingston Mar. 22, 1938 2,128,235 Dallenbach Aug. 26, 1938 2,137,005 Miller Nov. 15, 1938 2,174,374 Beggs Sept. 26, 1939 2,190,302 Waldschmidt Feb. 13, 1940 2,229,093 Knowles et a1. Jan. 21, 1941 2,250,647 Miller July 29, 1941 2,254,945 Hunt et a1 Sept. 2, 1941 2,409,715 Slack Oct. 22, 1946 2,414,137 Branson June 14, 1947 2,450,575 Hansell Oct. 5, 1948 2,465,084 Greiner Mar. 22, 1949 2,558,357 Grimm June 26. 1951 2,705,294 Schrader Mar. 29, 1955 2,722,624 Doolittle Nov. l, 1955 

